The present invention relates to testing of GSM (Global System for Mobile Communications) handsets, and in particular, to testing of such handsets with reduced requirements for signal interactions between the handset and testing resources.
Many of today's electronic devices use wireless signal technologies for both connectivity and communications purposes. Because wireless devices transmit and receive electromagnetic energy, and because two or more wireless devices have the potential of interfering with the operations of one another by virtue of their signal frequencies and power spectral densities, these devices and their wireless signal technologies must adhere to various wireless signal technology standard specifications.
When designing such wireless devices, engineers take extra care to ensure that such devices will meet or exceed each of their included wireless signal technology prescribed standard-based specifications. Furthermore, when these devices are later being manufactured in quantity, they are tested to ensure that manufacturing defects will not cause improper operation, including their adherence to the included wireless signal technology standard-based specifications.
For testing these devices following their manufacture and assembly, current wireless device test systems typically employ testing systems having various subsystems for providing test signals to each device under test (DUT) and analyzing signals received from each DUT. Some systems (often referred to as “testers”) include at least a vector signal generator (VSG) for providing the source signals to be transmitted to the DUT, and a vector signal analyzer (VSA) for analyzing signals produced by the DUT. The production of test signals by the VSG and signal analysis performed by the VSA are generally programmable (e.g., through use of an internal programmable controller or an external programmable controller such as a personal computer) so as to allow each to be used for testing a variety of devices for adherence to a variety of wireless signal technology standards with differing frequency ranges, bandwidths and signal modulation characteristics.
As part of the manufacturing of wireless communication devices, one significant component of production cost is costs associated with these manufacturing tests. Typically, there is a direct correlation between the cost of test and the sophistication of the test equipment required to perform the test. Thus, innovations that can preserve test accuracy while minimizing equipment costs (e.g., increasing costs due to increasing sophistication of necessary test equipment, or testers) are important and can provide significant costs savings, particularly in view of the large numbers of such devices being manufactured and tested.
Another critical factor in test costs is that of test times, and more particularly per-device test times, which must be minimized without compromising test integrity. Overall test times are determined by actual DUT testing activities (e.g., testing DUT performance in accordance with underlying system and DUT standards), DUT handling activities (e.g., connecting, disconnecting, moving of DUTs), and test preparation activities (e.g., initializing and/or synchronizing DUTs with the test system). Once test times have been optimally reduced for a single device, a next advance in reducing test time and cost involves testing multiple DUTs in a pipeline (e.g., overlapping sequences of distributed testing) or in parallel (e.g., concurrent testing of multiple DUTs) testing. This can include assembling and connecting one or more testers with additional signal routing circuitry (e.g., signal dividers, combiners, switches, multiplexors, etc.) as needed for providing receive (RX) signals to the DUTs and for receiving and analyzing transmit (TX) signals produced by the DUTs.
During the testing of cellular devices, e.g., mobile devices generally referred to as handsets, that rely on GSM technology, there is need for a testing system to make what is called a “mobile terminated call”, i.e., in which the tester calls the DUT and the DUT (as the point of termination) answers, or “terminates”, the call. Under normal use circumstances, when a GSM mobile device is called, the user physically responds to the call by pressing a button or touching a screen icon. In a test situation, other techniques are necessary. For example, some form of a mechanical apparatus could be used to achieve the button or screen icon press normally performed by a user. Alternatively, third-party software could be added to the DUT to enable it to answer the call automatically. Further alternatively, the test system can communicate with the DUT over an electrical connection (e.g., a micro-USB connector), which would enable the tester to determine that the DUT is “ringing” (receiving a call) and then issue a command over the electrical connection to answer the call. However, depending upon the state of completion of assembly of the DUT, such an electrical connection may not be available. Lastly, it may be possible to hand over a call from another radio-access technology (RAT), such as WCDMA, so that the call is already active when GSM mode testing is performed.
Accordingly, it would be desirable to have a technique capable of enabling testing of cellular devices, such as GSM handsets, without requiring mechanical manipulation or intervention (e.g., physical pressing of an electronic or electromechanical switch actuator, or touching of a touchscreen) or simulated presses (e.g., via software), as well as avoiding a need for signaling involved in call setup and completion that is otherwise extraneous to the DUT characteristics sought to be tested (e.g., a call handover from another (RAT).